Re: [CAD_CAM_EDM_DRO] Home /limit switches

Hi Bob,

A G61 or G31 "move until sense sw" command might work, if CNCpro
supports it (I don't recall). MaxNC does. In this case, a connection
to the proper pin (13) can be sensed, and movement stopped. Jon
mentions connecting (*AND* function) the encoder *I* channel with the
switch. This will "tighten up" the accuracy of the home position.

Alan KM6VV


Robert Allen & Marsha Camp wrote:

>
> Jon Elson wrote:
>
> > Robert Allen & Marsha Camp wrote:
> >
> > > Anyone have a recommendation for high accuracy home
> > > switches, will regular micro switches work? I have CNCpro
> > > which apparently goes to the switch then backs up a set
> > > distance so the home switch must be repeatable to at least
> > > .001" I would think maybe closer.
> >
> > You may want to add a second sensor, probably an optical
> > 'slot' sensor that detects a disc with one slot on the motor.
> > An and gate can combine the coarse switch and the fine
> > sensor to get a more repeatable position.
> >
> > Jon
> >
>
> I think the encoder has an index mark (ch. A, ch. B and I) but I don't think
> CNCpro can use it.
> I wonder if there is a way to use it. I don't quite see how I can get
> movement back to the index mark without building some kind of circuit that
> stops the input to the gekkos when the home switch is reached and the table
> backs up a set distance.
> I would have to set the back up distance to go further than the index mark
> and stop the gekko input, how, a transistor shorting the input from the
> software high or low as needed. This might be accurate if the homing speed
> was slow enough. I see this getting a lot more complicated than I thought it
> would be.
> Thanks Bob
> KB1FRW